1. Field of the Invention
The present invention is directed to an adjustable damping valve device of a vibration damper which includes an emergency operation valve.
2. Background of the Invention
US2011/0168935A1 describes an adjustable damping valve device which is traversed by flow in two directions. A main stage valve body of the damping valve device is loaded by a mechanical spring force and an opposing actuator force. The resulting actuation force acts in opposition to a hydraulic force that likewise comprises two opposed force components. The main stage valve body has pressure-loaded surfaces which are loaded by damping medium. In so doing, one pressure-loaded surface is used for a closing force component for both through-flow directions. The ratio of the maximum achievable damping force to minimum damping force, also known as spread, is increased by this advantageous design of the damping valve device.
Overall, the adjustable damping valve device is distinguished by its simple construction. In particular, the damping valve device has an emergency operation function in that a large damping force is always adjusted in case of failure of the energy supply for the actuator so that the vehicle can be safely controlled. However, a comparatively large amount of energy must be applied to achieve a soft damping force setting. This operating concept is disadvantageous given the unlikelihood that emergency operation will ever take place.
US2010/0252766A1, the entire content is incorporated herein by reference, shows an adjustable damping valve device having an emergency operation valve which closes an outlet from a control space in the event of failure of the energy supply of the actuator; a throttle resistance of an outlet cross section connected in parallel with the emergency operation valve determines the pressure level in the control space and, therefore, the resulting hydraulic damping force component at the main stage valve body.
It is an object of the present invention to improve a damping valve constructed as per US2011/0168935A1 in such a way that, on the one hand, a soft damping force setting is possible with a low expenditure of energy and, on the other hand, an emergency operation function is possible in case of failure of the energy supply.